package backdate;

import java.util.LinkedList;
import java.util.List;

//https://leetcode.cn/leetbook/read/illustration-of-algorithm/5dy6pt/
//给你二叉树的根节点 root 和一个整数目标和 targetSum ，找出所有 从根节点到叶子节点 路径总和等于给定目标和的路径。
//叶子节点 是指没有子节点的节点。
public class LCR_153二叉树中和为目标值的路径 {
    public class TreeNode {
      int val;
      TreeNode left;
      TreeNode right;
      TreeNode() {}
      TreeNode(int val) { this.val = val; }
      TreeNode(int val, TreeNode left, TreeNode right) {
          this.val = val;
          this.left = left;
          this.right = right;
      }
    }
    //先序遍历 + 路径记录
    class Solution {
        LinkedList<List<Integer>> res = new LinkedList<>();
        LinkedList<Integer> path = new LinkedList<>();
        public List<List<Integer>> pathTarget(TreeNode root, int target) {
            recur(root, target);
            return res;
        }
        private void recur(TreeNode root, int tar) {
            if(root == null) return;
            path.add(root.val);
            tar -= root.val;
            if(tar == 0 && root.left == null && root.right == null)
                res.add(new LinkedList<>(path));
            recur(root.left,tar);
            recur(root.right,tar);
            path.removeLast();
        }
    }
}
